Tesco Everyday Value Frozen Cheese and Tomato Pizza is 60p. If you use decent cheese, decent tomato paste and reasonable flour etc you will have trouble matching that.
Yes, but then you are comparing apples to oranges aren't you?
A decent quality ready made pizza (Pizza Express brand for example) can set you back the best part of a fiver. If you fed a family of four on five with older, bigger DC on those it would be a very expensive ready meal. You could make a comparable quality, exceptionally good pizza from scratch for much, much less.
I think the problem now is that we have become so aspirational about food that we expect (and think we deserve) complex recipes and fantastic variety every night of the week. My cupboards and fridges are bursting with every kind of pot, jar and bottle of cooking ingredient under the sun because I like to cook and I like to be able to make anything I want at the drop of a hat without having to trawl the shops for sun dried tomatoes or harissa or tahini or whatever, first. But it has undoubtedly costs me hundred and hundreds of pounds each year to be able to do that, on top of the basic meat/veg and everyday ingredients that I would buy anyway. So much of this stuff gets opened, a few dollops used for a specific recipe and then stuck back in the fridge/cupboard for years months and it often doesn't get used before it spoils because I rarely cook the same thing with enough frequency to use it all up.
That's okay, I can afford it. But if I were on a low income I would have to think very carefully about which ingredients I prioritised and I'd have to commit to eating stuff with harissa or tahini or whatever on a bit of a loop until it was gone. Yet we are encouraged/inspired by aspirational cooking programmes to eat differently night in, night out.
Listening the the self-style nutritonal expert on Steve Wright's show yesterday talking about what should be in our children's packed lunches for example??seriously, so many kids have two full time working parents now and these 'experts' want us to fanny around making homemade oatcakes and healthy muffins and hummus and grating veg into wraps, and doing things with avocados?
If we ever had packed lunches it was a jam or a cheese sandwich and an apple, and bag of crisps if we were lucky. 
Years ago everything was cooked from scratch because there was no alternative, and in many parts of the world that is still very much the case, but the food is/was very simple and very repetitious. Meat is/was a precious commodity that is/was only served occasionally or eeked out and served with big quantities of veg, pulses, grains, potatoes etc.